ABB RET670 Applications Manual page 144

Section 3
IED application
138
Table 44: 1 A channels: input with minimum operating down to 20 mA
Operating Stabilizing
TripPi
voltage resistor R
ckup
ohms
20 V 1000
40 V 2000
60 V 3000
80 V 4000
100 V 5000
150 V 6000
200 V 6800
Table 45: 5 A channels: input with minimum operating down to 100 mA
Operating Stabilizing
TripPi
voltage resistor R1
ckup
ohms
20 V 200
40 V 400
60 V 600
80 V 800
100 V 1000
150 V 1500
200 V 2000
The current transformer saturating voltage must be at least 2 · TripPickup to have
sufficient operating margin. This must be checked after calculation of TripPickup.
When the R value has been selected and the TripPickup value has been set, the
sensitivity of the scheme IP can be calculated. The IED sensitivity is decided by the
total current in the circuit according to equation 35.
å
= × + +
IP n IR ( Ires lmag
EQUATION1747 V1 EN
where:
n is the CT ratio
IP primary current at IED pickup,
Table continues on next page
Operating Stabilizing
current level resistor R
1 A ohms
0.020 A --
0.020 A 1000
0.020 A 1500
0.020 A 2000
0.020 A 2500
0.020 A 3750
0.029 A 5000
Operating Stabilizing
current level resistor R1
5 A ohms
0.100 A 100
0.100 A 200
0.100 A 300
0.100 A 400
0.100 A 500
0.100 A 750
0.100 A 1000
)
1MRK504116-UUS C
Operating Stabilizing
current level resistor R
1 A ohms
-- --
0.040 A --
0.040 A 600
0.040 A 800
0.040 A 1000
0.040 A 1500
0.040 A 2000
Operating Stabilizing
current level resistor R1
5 A ohms
0.200 A --
0.200 A 100
0.200 A 150
0.200 A 200
0.200 A 250
0.200 A 375
0.200 A 500
Application manual
Operating
current level
1 A
--
--
0.100 A
0.100 A
0.100 A
0.100 A
0.100 A
Operating
current level
5 A
--
0.400
0.400 A
0.400 A
0.400 A
0.400 A
0.400 A
(Equation 35)